Stainability of different ceramic materials against mouth rinses and effect of polishing after staining

How do various mouth rinses influence the color stability of CAD-CAM resin-based restorative materials?

STATEMENT OF PROBLEM

The color stability of computer-aided design and computer-aided manufacture (CAD-CAM) resin-based materials can be affected by their composition and exposure to different mouth rinses. However, the impact of different mouth rinse formulations on these materials remains unclear.

PURPOSE

The purpose of this in vitro study was to investigate the effect of different mouth rinses on the color stability of CAD-CAM resin-based materials over time.

MATERIAL AND METHODS

A total of 180 specimens of 5 CAD-CAM resin-based materials were fabricated: a polymer-infiltrated ceramic network (PICN) (Vita Enamic; ENA), resin nanoceramics (GC Cerasmart; CERA, Brilliant Crios; BRC), a resin nanohybrid (Grandio; GRD), and a resin composite (KZR-CAD HR2; KZR). A lithium disilicate ceramic (IPS e.max CAD; EMX) served as the control (n=30). Specimens were immersed in alcohol-containing (Listerine Cool Mint; LIS), alcohol-free (Oral-B complete; ORLB), zinc-chloride containing (Pharmol Zn; PHR), hypochlorous acid-containing (Briotech Pure; BRT) mouth rinses, and artificial saliva (CON) for 12 hours (t0.5), 2.5 days (t2.5), and 5 days (t5) of simulated exposure equivalent to 1, 5, and 10 years. Color differences (ΔE00) were calculated at each time point. The effects of material, mouth rinse, and time were analyzed using 3-way robust ANOVA with Bonferroni post hoc tests (α=.05).

RESULTS

EMX exhibited the highest color stability, while the GRD showed the largest discoloration (P<.001). LIS and ORLB mouth rinses caused significantly higher ΔE00 values than other solutions (P<.001). Discoloration increased with longer exposure times (P=.001). Among all groups, BRC immersed in LIS exhibited the most pronounced color change, while EMX in CON showed the least (P=.001).

CONCLUSIONS

CAD-CAM resin-based materials undergo a larger color change than lithium disilicate ceramic, with variations depending on composition and mouth rinse type. While alcohol-containing mouth rinse (LIS) induced the highest discoloration, particularly in the resin nanoceramic (BRC), the highest discoloration after a simulated prolonged exposure of 10 years was observed in the resin nanohybrid (GRD). Notably, the alcohol-free ORLB also led to significant discoloration, suggesting that other ingredients beyond alcohol contribute to staining.

Color stability of frequently used aesthetic restorative materials following in vitro exposure to chlorhexidine- and octenidine-based mouthrinses

BACKGROUND

Long-term color match is one of the most important characteristics of aesthetic restorative materials as discoloration constitutes a primary reason for otherwise unnecessary replacements. The aim of the present in vitro study was to evaluate the color stability of frequent dental materials (ceramic, composite, orthodontic adhesive) induced by common antiseptic mouthrinses taking into account black tea consumption and mechanical cleaning.

METHODS

Twenty-four disc-shaped specimens (8 × 2 mm) were made of the materials Ceram.x Spectra™ ST HV, Ceram.x Spectra™ flow, Ceramill® Zolid HT+ PS and Unitek™ Transbond™ LR. Each of the following solutions was tested on six pieces per material: Chlorhexamed forte (CHX), octenident® (OCTD), octenimed® (OCTM) and artificial saliva (control). Dental samples underwent a total of 30 discoloration cycles in which they were alternatively placed into artificial saliva, black tea and respective mouthrinse or only in artificial saliva. After every 10 cycles, discs were mechanically cleaned with toothbrush and toothpaste. After 30 cycles, dental specimens were submitted to professional polishing. Color shifts were measured at different time-points using the VITA Easyshade® V spectrophotometer and displayed as total color difference ∆E (mean ± standard error). A post-hoc Tukey test (⍺ = 0.05) was applied to the mean ∆E values after 30 cycles to determine discoloration discrepancies between various mouthrinses as well as the control. Moreover, photos of individual discs were taken at all measurement times to visualize potential color changes by eye.

RESULTS

All mouthrinses showed major color shifts in the clinically visible range compared to the control on all different dental materials tested. However, CHX caused significantly more discoloration than OCTM and OCTD. Established color changes could be almost completely removed by simple brushing and even further by professional polishing to clinically acceptable levels on all tested materials.

CONCLUSIONS

Prolonged application of antiseptic mouthrinses may cause discoloration on different restorative materials. To maintain aesthetically satisfying conditions, patients should be educated about the importance of daily mechanical tooth brushing and regular professional polishing.

Effect of simulated gastric acid exposure on the hardness, topographic, and colorimetric properties of machinable and pressable zirconia-reinforced lithium silicate glass-ceramics

STATEMENT OF PROBLEM

The effects of gastric acid on the hardness, topographic, and colorimetric properties of zirconia-reinforced lithium silicate glass-ceramics (ZLSs) for dental restorations remain unknown.

PURPOSE

The purpose of this in vitro study was to investigate the effect of simulated gastric acid exposure on the microhardness, surface roughness, color stability, and relative translucency of ZLSs.

MATERIAL AND METHODS

Two pressable ZLSs (VITA AMBRIA, VA and Celtra Press, CP) and 2 machinable ZLSs (VITA Suprinity, VS and Celtra Duo, CD)(n=64) were randomly allocated to artificial saliva (control) or gastric juice immersion groups simulating 10 and 20 years of clinical exposure. Microhardness (Hv) was measured with a Vickers hardness device, and surface roughness (Sa) was recorded with an optical profilometer. The color stability (ΔE00) and relative translucency parameter (RTP) were measured with a spectrophotometer. Data for Hv, Sa, and RTP were analyzed by repeated 2-way ANOVA, and data for ΔE00 were analyzed by 2-way ANOVA. Post hoc comparisons were obtained from Tukey HSD and Student t tests (α=.05).

RESULTS

Machinable ZLSs exhibited greater Hv after the simulated gastric acid challenge than pressable ZLSs. Sa was significantly impacted by material type (P=.001), storage media (P=.050), and their interaction (P<.001). ΔE00 was significantly affected by the type of simulated aging media (P<.001). After 20 years of simulated gastric acid aging, all ZLS materials surpassed the ΔE00 perceptibility threshold but did not exceed the ΔE00 acceptability threshold. VS displayed significantly lower RTP than other ZLS materials at all time points (P<.001).

CONCLUSIONS

The topographic and colorimetric characteristics of ZLS were significantly altered by exposure to simulated gastric acid.

Effect of Successive At-home Bleaching Sessions on the Surface Properties, Biaxial Flexural Strength, and Reliability of CAD-CAM Monolithic Materials

Although at-home bleaching can recover the optical properties of stained CAD-CAM monolithic materials, little is known about its impact on their surface and mechanical properties, especially when successive sessions are performed. This study evaluated the effect of successive at-home bleaching sessions on the microhardness, roughness, topography, biaxial flexural strength (BFS), and reliability of CAD-CAM monolithic materials. Disks from Lava Ultimate (LU), Vita Enamic (VE), and IPS Empress CAD (EMP) were fabricated and submitted to up to three bleaching sessions. At-home bleaching was performed with 10% carbamide peroxide, and each session consisted of one application for 10 hours/day for 14 days. The analyses of the aforementioned parameters were assessed before and after the first, second, and third bleaching sessions, except for BFS, which was evaluated at baseline and after the third session. The Weibull modulus was calculated from the BFS data. The microhardness of the three materials as well as the roughness of LU were not affected by the sessions, whereas the roughness of VE and EMP increased from the second session. All materials displayed topographic changes, which became more pronounced with the increase in the number of sessions. Although bleaching decreased the BFS of the materials, it did not adversely affect their reliability. Successive at-home bleaching sessions with the protocol used in the present study cannot be considered a safe procedure for the materials evaluated.

Color and surface stainability of additively and subtractively manufactured interim restorative materials against mouth rinses

STATEMENT OF PROBLEM

Interim restorations are often used along with mouth rinses during the healing period following surgical procedures. However, evidence regarding the color and surface properties of digitally fabricated interim restorations after oral rinsing is lacking.

PURPOSE

The purpose of this in vitro study was to evaluate whether different mouth rinses could affect the color and surface roughness of milled and printed interim restorations after simulated oral rinsing.

MATERIAL AND METHODS

Disk-shaped specimens (Ø15×2 mm; N=180) were fabricated by using conventional (Jet Tooth Shade), milled (Yamahachi PMMA Disk), and printed (NextDent C&B) resin materials. All resin specimens were divided into 3 different groups according to the rinsing material: distilled water, whitening mouth rinse (Listerine Healthy White), and conventional mouth rinse (Listerine Cool Mint). The specimens were further allocated into short- and long-term subgroups, and oral rinsing simulation was performed (n=10). Short-term rinsing simulated the conditions in a usual interim restoration period, and long-term rinsing was performed to evaluate the properties of the interim materials. The color differences (CIEDE2000, ΔE00) between the baseline and each time point were determined by using a spectrophotometer. The surface roughness of the tested specimens was measured by using a confocal laser scanning microscope. Kruskal-Wallis and Friedman tests with nonparametric pairwise comparisons were used to analyze the data (α=.05).

RESULTS

On simulation of a 6-month use of the mouth rinse, the color change in the milled resin did not differ from that in the conventional resin (P>.334), but the printed resin showed a significantly greater color change than the other resins (P<.007). The greatest color change with the printed resin was observed when a conventional mouth rinse was used. However, all color changes were below a perceptible threshold of 1.30. When daily rinsing for 14 years was simulated, all resin groups showed a perceptible color change when conventional mouth rinse was used, and the printed resin showed the greatest median ±interquartile range ΔE00 (2.24 ±0.2). In both short- and long-term simulations, the printed resin rinsed with the conventional mouth rinse showed significantly greater roughness than that rinsed with distilled water (P<.009).

CONCLUSIONS

The printed resin showed higher stainability than the conventional resin, and the color change was greatest with the conventional mouth rinse. However, in 6 months of daily mouth rinse simulation, all the tested resin materials exhibited imperceptible color change and clinically acceptable surface roughness.

Effect of mouth rinses on the stainability of monolithic lithium disilicate glass-ceramics with different surface treatments: An in vitro study

STATEMENT OF PROBLEM

Mouth rinses have been reported to cause tooth surface discoloration. However, information regarding their effect on the stainability of monolithic glass-ceramics with different surface treatments is lacking.

PURPOSE

The purpose of this in vitro study was to assess the effect of mouth rinses on the color change of milled and pressed monolithic lithium disilicate glass-ceramics with different surface treatments.

MATERIAL AND METHODS

Fifty-six Ø12×1.5-mm disk specimens were fabricated using 2 different processing techniques: milling and pressing. Each group was subdivided into 2 subgroups according to surface treatments: glazed and polished. Specimens were then immersed in 2 different types of mouth rinse (n=7): chlorhexidine (CHX) and Listerine (LST). Color parameters were assessed using a digital spectrophotometer. Color difference (ΔE00) was calculated and compared with perceptibility (ΔE00=0.8) and acceptability (ΔE00=1.8) thresholds. The data were analyzed using ANOVA and Tukey post hoc tests (α=.05).

RESULTS

The color difference (ΔE00) was significantly affected by the type of processing technique, surface treatment, and mouth rinse (P<.001) and their interaction (P=.008). All ΔE00 values were below the selected clinical acceptability threshold (ΔE00=1.8). Milled groups (ΔE00=1.13) showed greater discoloration than pressed groups (ΔE00=0.86). Glazed specimens (ΔE00=0.70) were more resistant to discoloration than polished specimens (ΔE00=1.28) and immersion in CHX (ΔE00=1.09) led to more discoloration than immersion in LST (ΔE00=0.89).

CONCLUSIONS

The color of milled and pressed monolithic lithium disilicate glass-ceramics with different surface treatments was affected by using CHX and LST mouth rinses. Glazed lithium disilicate glass-ceramics showed less staining compared with those that were polished. Specimens immersed in CHX showed more discoloration than those immersed in LST.

3D Printing of CNT- and YSZ-Added Dental Resin-Based Composites by Digital Light Processing and Their Mechanical Properties

This study demonstrates the successful 3D printing of dental resin-based composites (DRCs) containing ceramic particles using the digital light processing (DLP) technique. The mechanical properties and oral rinsing stability of the printed composites were evaluated. DRCs have been extensively studied for restorative and prosthetic dentistry due to their clinical performance and aesthetic quality. They are often subjected to periodic environmental stress, and thus can easily undergo undesirable premature failure. Here, we investigated the effects of two different high-strength and biocompatible ceramic additives, carbon nanotube (CNT) and yttria-stabilized zirconia (YSZ), on the mechanical properties and oral rinsing stabilities of DRCs. Dental resin matrices containing different wt.% of CNT or YSZ were printed using the DLP technique after analyzing the rheological behavior of slurries. Mechanical properties such as Rockwell hardness and flexural strength, as well as the oral rinsing stability of the 3D-printed composites, were systematically investigated. The results indicated that a DRC with 0.5 wt.% YSZ exhibits the highest hardness of 19.8 ± 0.6 HRB and a flexural strength flexural strength of 50.6 ± 6 MPa, as well as reasonable oral rinsing steadiness. This study provides a fundamental perspective for designing advanced dental materials containing biocompatible ceramic particles.

Physical, Optical, and Mechanical Properties of Ceramic Materials after Coffee Immersion and Evaluation of Cleaning Impact with Different Oral Hygiene Tools

This study aimed to evaluate the effect of three oral hygiene tools, a regular toothbrush, an electronic toothbrush, and mouthwash, on the color stability of three different computer-aided design (CAD) and computer-aided manufactured (CAM) ceramic blocks. Feldspathic ceramic (Vita Triluxe Forte), hybrid resin ceramic (Vita Enamic), and lithium disilicate glass-ceramic (IPS e.max CAD) were used in this study. A CAD/CAM system and 81 (27 of each material) samples of ceramic blocks were used. All samples were immersed in black coffee for 15 days, and the coffee was changed twice per day. Using a spectrophotometer probe, samples on a grey background were scanned, and physical properties like surface hardness and depth were measured using interferometry and a 3D non-contact surface metrology. After 30 days of application of oral hygiene tools, instruments were used to measure various physical, mechanical, and optical properties. Vita Triluxe had the highest average color variation values (ΔE₀₀) after 15 and 30 days of immersion in coffee in both regular and electronic toothbrushes. Moreover, IPS e.max CAD had the least ΔE₀₀ values with no significant differences among the groups. The surface roughness (Ra) of the Vita Enamic ceramic increased when using a regular toothbrush, and the surface height (Rz) for the Vita Enamic ceramic increased when an electronic toothbrush was used. IPS e.max CAD had the greatest modules of elasticity forces, and Vita Triluxe Forte had the lowest when used with a regular toothbrush. The ΔE₀₀ values of the tested materials were minimally increased or decreased after 30 days of cleaning, and all were clinically acceptable. Ra and Rz were the highest for Vita Enamic in comparison to the other groups. The highest percentage in IPS e.max CAD was associated with a type 1 fracture, whereas type 3 was predominantly observed with Vita Enamic, and type 2 in the Vita Triluxe group without significant differences.